LOS ANGELES, Aug. 4 (Xinhua) -- Traveling by car increases global temperatures more than by plane, but only in the long run, according to new findings released by the American Chemical Society on Wednesday.
The study, published in the August issue of Environmental Science & Technology, said that in the long run, the global temperature increase from a car trip will be on average higher than from a plane journey for the same distance.
"Car travel emits more carbon dioxide than air travel per passenger mile. As carbon dioxide remains in the atmosphere longer than the other gases, cars have a more harmful impact on climate change in the long term," said Kleefeld from the International Institute for Applied Systems Analysis in Austria.
However, in the short run, traveling by air has a larger adverse impact on climate because airplanes only affect short-lived warming processes at high altitudes.
In the first years after the journey, air travel increases global temperatures four times more than car travel. Passenger trains and buses cause four to five times less impact than automobile travel for every mile a passenger travels, according to the study.
"As planes fly at high altitudes, their impact on ozone and clouds is disproportionately high, though short lived. Although the exact magnitude is uncertain, the net effect is a strong, short-term temperature increase," said Dr. Jens Borken-Kleefeld, lead author of the study.
To determine the impact of different means of transport, the researchers use, for the first time, a suite of climate chemistry models to monitor the climate effects of all long- and short-lived gases, aerosols and cloud effects, not just carbon dioxide, resulting from transport worldwide.